BPT PEC BI and Nuki Opener

We moved to an office which has an BPT PEC BI intercom installed. We successfully installed Nuki Lock (4th) and Nuki Bridge and now we wanted to attache the Nuki Opener to the intercom.

Unfortunately Nuki does not support BPT PEC BI … but a lot of other BPT systems. So we tried our luck (without success).

Yellow is: ⌐ B (left of B is “reversed not sign”)
White is: B ¬ (right of B is “not sign”)
Brown is: :bell: (Bell)
Green is: - (Minus)
Pink and black cable are not connected at all.
“AL” on the board even does not have anything attached.

We tried to connect:
Yellow with black (on Nuki Opener)
White with violet
Replace brown with green (Nuki Opener) and
Connect brown and yellow (Nuki Opener) with clip.
Green with blue (Nuki Opener)

Do you have any idea? Even which device I should choose on the Nuki App for connecting the Opener?

We also found out that we intercom only allows to open the front door after the bell rang.

Many thanks for any help!